南海北部神狐海域晚末次冰期以来有孔虫特征及其对古海洋环境的指示

发布时间：2018-06-03 23:02

本文选题：有孔虫组合 + 稳定同位素　；参考：《海洋地质与第四纪地质》2017年02期

【摘要】：南海北部陆坡有大量高分辨率沉积记录,对研究全球变化响应及驱动机制有着举足轻重的作用。本研究选取南海北部神狐海域2007年水合物钻探区Site 6A站位柱状沉积物,开展有孔虫群落、稳定同位素及AMS14 C分析研究,试图了解该区域晚末次冰期以来古海洋和古气候演化历史。结果显示,Site 6A站位柱状沉积物中底栖有孔虫连续分布,优势属种突出,丰度、分异度波动明显。沉积物底界为MIS3期约50kaBP,全新世沉积速率最高,为13.37cm/ka,在MIS2期可能存在由水合物分解导致的地层缺失。有孔虫氧碳同位素特征恢复了冰期/间冰期气候旋回变化及冰盖体积变化,也指示该海域沉积环境氧化还原状况基本不变。通过对具有特殊生态意义的底栖有孔虫Uvigerina、Cibicidoides、Bulimina的相对丰度分析,结合似瓷质壳体百分含量及浮游有孔虫碳同位素,得出在末次冰期40kaBP东亚夏季风增强带来大量降雨,陆径流量增大导致古生产力增加。12~17ka的古生产力高值可能与增强的冬季风携带大量陆源碎屑沉积有关,并使得北大西洋低温、低氧、高营养盐的水团对该站位影响更大。
[Abstract]:There are a large number of high-resolution sedimentary records on the northern slope of the South China Sea, which plays an important role in the study of global change response and driving mechanism. In this study, the foraminifera community, stable isotope and AMS14 C were studied in the columnar sediments of the Site 6A station in the Shenhu area of the northern South China Sea in 2007. This paper attempts to understand the paleoceanic and paleoclimate evolution history in the region since the late last glacial epoch. The results showed that benthic foraminifera were distributed continuously in columnar sediments of site Site 6A, and the dominant genera were prominent, abundance and differentiation fluctuated obviously. The bottom boundary of the sediments is about 50 MIS2 in the MIS3 period and the highest deposition rate in the Holocene is 13.37 cm / kg. During the MIS2 period there may be stratigraphic defects caused by hydrate decomposition. The oxygen and carbon isotopic characteristics of foraminifera recovered the climatic cycle and ice sheet volume change during the glacial / interglacial period, indicating that the redox status of the sedimentary environment in the sea area was basically unchanged. Based on the analysis of the relative abundance of the benthic foraminifera Uvigerinia Cibicidoides Bulimina, combined with the percentage content of porcelain shell and the carbon isotope of planktonic foraminifera, it is concluded that the enhancement of 40kaBP East Asian Summer Monsoon during the last glacial period brought a great deal of rainfall. The high value of paleoproductivity due to the increase of land runoff may be related to the strong winter monsoon carrying a large amount of continental clastic deposits, and the water masses with low temperature, low oxygen and high nutrients in the North Atlantic will have a greater influence on the station.
【作者单位】：中国科学院天然气水合物重点实验室中国科学院广州能源研究所;中国科学院大学;国土资源部天然气水合物重点实验室青岛海洋地质研究所;海洋国家实验室海洋矿产资源评价与探测技术功能实验室;
【基金】：国家自然科学基金项目(41273022) 中国石油-中科院科技合作项目(2015A-4813) 中国科学院广州能源研究所所长创新基金培育专项(y307p51001)
【分类号】：P736.22

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